Abstract: The UDH mercury-free catalyst was prepared in a 10 L synthesis tank and was characterized by ICP-AES, BET, SEM and TEM. The comparison test for acetylene hydrochlorination with an industrial HgCl2 catalyst was conducted in a single pipe reactor under the same experimental conditions. The characterization results show that the UDH mercury-free catalyst has a micropore structure, the pore diameter is 2 nm, and the particle size of active component is 4 nm. The catalytic tests indicate that the VCM selectivity of UDH mercury-free catalyst is more than 99% which equals to that of the industrial HgCl2 catalyst. The C2H2 conversion of industrial HgCl2 catalyst is more than 98% in the first 900 hours, but declines in the following 700 hours; while the C2H2 conversion of UDH mercury-free catalyst reduced slowly from 98% to 89% in the whole 1 600 hours runing, thus the mercury-free catalyst has better stability.